Lasers are becoming increasingly used in industrial and military settings. Lasers are commonly used in industrial processes, for example, to cut and weld metals and other substances, particularly in the automotive, aerospace, appliance and shipbuilding industries. Lasers may also be useful for rock drilling for mining and/or oil and gas exploration purposes. In military settings, lasers are particularly useful in precision strike situations where it is desirable to minimize collateral damage. Lasers have also been mounted on spacecraft, aircraft, ships and land-based vehicles for other military-related purposes, including missile defense.
Solid-state lasers (SSLs), in particular, have received particular attention in recent years. Such lasers typically include a solid-state lasing medium (crystal or glass) doped with suitable rare-earth ions that are optically pumped with light emitting from one or more semiconductor diodes to produce coherent light. Although SSLs are effective for many purposes, design issues may arise in dealing with waste heat produced within the lasing medium. This heat can cause various types of thermo-mechanical and thermo-optical distortions in the laser, resulting in thermal lensing, mechanical stresses, depolarization and other undesirable effects. In extreme cases, these effects could result in degradation in beam quality (BQ), reduced laser power and/or possible fracture of the SSL lasing medium.
One type of SSL used in high average power (HAP) applications is the so-called “disk laser”, in which the lasing medium is formed into a disk shape that can be exposed to pump radiation for amplification of a laser beam. FIGS. 1(a) and 1(b) show exemplary disk amplifier modules that transmit and reflect laser light, respectively. In a transmissive disk amplifier, the laser beam passes through the lasing medium. Heat is removed by flowing suitable cooling medium (gas or liquid) over the large faces of the disk. In a reflective disk amplifier (also know as active mirror), one face of the disk may be provided with a reflective coating such that the laser beam exists through the face opposite the coating after making two passes through the disk. Heat is primarily transmitted through the coating to a heat exchanger or the like. In disk lasers, the temperature gradient is generally parallel to the laser beam path, which makes the disk lasers far less susceptible to many of the thermo-mechanical distortions discussed above. Design issues still remain, however, in obtaining improved laser performance and reducing the price of the laser. In particular, it is desirable to provide uniform optical gain across the aperture of the lasing medium to obtain good beam quality. Moreover, it is desirable to reduce the cost and complexity of the laser by reducing reliance upon custom-made components, by improving access to power and coolant within the laser assembly, and through other techniques.
Accordingly, it is desirable to create a solid-state laser with improved distribution of pump radiation across the lasing medium. Moreover, it is desirable to create a laser design that provides convenient access to power and coolant for the sources of pump radiation. In addition, it is desirable to create a laser that can be assembled from readily-available components. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.